docs: def activity(name=None, namespace=None, identifier=None, location=None):
      """Make a subject/object modifier dictionary.
  
      :param str name: The name of the activity. If no namespace given, uses BEL default namespace
      :param Optional[str] namespace: The namespace of the activity
      :param Optional[str] identifier: The identifier of the name in the database
      :param Optional[dict] location: An entity from :func:`pybel.dsl.entity` representing the location of the node
      :rtype: dict
      """
      rv = _activity_helper(ACTIVITY, location=location)
  
      if name or (namespace and identifier):
          rv[EFFECT] = Entity(
              namespace=(namespace or BEL_DEFAULT_NAMESPACE),
              name=name,
              identifier=identifier,
          )
  
      return rv